The present invention relates to a chair with movable armrests that are comfortable and easy to use.
In recent years, desktop OA (office automation) equipment, such as personal computers, has been used more frequently in offices and the like. As chairs become more functional, reclining against the back of a chair has been found to be the most comfortable position for operating a personal-computer keyboard or the like. Because a person in a chair tends to work at a desk with his or her arms stretched forward, it is preferable that the person use part of the desktop as an armrest to reduce the load on the arms. However, if the person cannot place the arms on the desktop because he or she is in a reclined position, the desktop is not sufficiently wide, or the person cannot get close enough to the desktop due to occupied space under the desk, the person cannot use the desktop as an armrest. Particularly when operating a keyboard, a person in a chair tends to hold his or her arms closer together than the distance between his or her shoulders. Thus, armrests that can be placed in front of the person are needed.
Chairs have been proposed with armrests that can be moved from their original position to in front of a person in the chairs when he or she operates a personal computer. Such chairs include those with armrests consisting of arm supports attached to the sides of the chair body, and arm mounts, each of which are rotatably attached to an arm support using one shaft, and those that are designed to rotatably connect an arm support to a connecting member using one shaft, and an arm mount to the connecting member also using one shaft, with the connecting member interposed between the arm support and arm mount.
However, because a chair that is adapted to turn an arm mount using one shaft is unstable and weak, the shaft is likely to be damaged if a load is exerted at a point too far from the shaft. In addition, the range of rotation of the arm mount around the shaft is limited, so that the arm mount cannot be moved far in front of a person in the chair.
A chair is available that has an arm mount that turns around two shafts at both ends of one free-end link connecting an arm support and the arm mount together. Although such an arrangement allows the arm mount to move more widely, it poses the following problem: part of the arm mount protrudes so far outward during its rotation from the side of a person in the chair to his or her front, that he or she must move the chair back or assume an uncomfortable position to prevent the mount from interfering with the desktop and him or herself In addition, the arm mount may be damaged if a load is applied to the mount when it is protruding far outward. If the distance between the two shafts is decreased to solve these problems, the movement of the arm mount is limited to a narrow range, thus preventing the arm mount from being fully moved from its regular position to in front of the person in the chair. As is obvious from the above, conventional armrests are uncomfortable and difficult to use.
In view of the foregoing, the present invention is directed to a chair with armrests that can be used as necessary by controlling the arm mounts so that they follow the figure of the person in the chair.
A chair according to the present invention includes a chair body with armrests attached to its sides. The armrests include arm supports and arm mounts. The arm supports are attached to the sides of the chair body and support the arm mounts. A controlling means for controlling at least the arm mounts so that they can move around a person in the chair in a regular path between a first use position on the sides of the person sitting on the chair body and a second use position in front of the person, is provided between the chair body and the arm supports or in part of the armrests.
Such an arrangement allows at least the arm mounts to move around the person in a chair between the first use position on the sides of the person and the second position in front of the person. Thus, the person in the chair places his or her arms on the arm mounts in the first use position when he or she is performing no operation at his or her desk, and the person can move the arm mounts to the second use position and effectively use them as armrests when he or she performs an operation at his or her desk, such as using a personal computer. Because the arm mounts follow a substantially regular path under the control of the controlling means when moving to the second use position, it is not necessary for the person in the chair to avoid the arm mounts. Moreover, the arm mounts make only necessary motions, without protruding too far forward or to the side, thus increasing armrest stability.
In particular, to appropriately move only the arm mounts with the mounts stably supported by the arm supports, it is desirable that, using an arm supporting means, the arm supports support the arm mounts so that the arm mounts can move between the first and second use positions and the controlling means can control the movement of the arm mounts through the use of the supporting means.
A preferable method of properly moving an arm mount is to use a link mechanism as a supporting means and controlling means by connecting the arm mount through the link mechanism to an arm support. To make the link mechanism extremely simple, it is desirable that it constitute first and second link elements that are rotatably attached to the connections between the arm support and the arm mount, that at least the first link element be used as the supporting means, and that the first and second link elements constitute the controlling means.
To appropriately rotate an arm mount using such a link mechanism, it is preferable that the tetragon formed by the straight lines connecting attachment holes in the first and second link elements not be a parallelogram. To allow the arm mount to follow an appropriate path, a preferable link mechanism should meet the following requirements: the first link element rotates a hole for attachment to the arm mount from an obliquely rear outside position to an inside position, With a hole for attachment to the arm support at the center of rotation; the second link element rotates the hole for attachment to the arm mount from an obliquely rear outside position to an obliquely front outside position, with the hole for attachment to the arm support at the center of rotation; and the straight line connecting the hole for attaching the first link element to the arm mount and the hole for attaching the second link element to the arm mount rotates between the first and second use positions, from the position at which the line is nearly in the longitudinal direction of the arm mount to the position at which the line is nearly in the lateral direction of the arm mount.
To effectively limit the range of rotation of the first and second link elements through the use of the link mechanism, the first and second link elements are adapted so as to interfere with each other at or near the first and second use positions.
To improve arm mount support strength and maintain a regular arm mount path, it is preferable that the second link element, together with the first link element, supports the arm mounts, and that the link mechanism uniquely determines the arm mount path.
Another link mechanism that allows the arm mounts to move in a substantially regular path, while allowing slight deviation from the path is adapted so that the distance between the attachment holes in the second link element changes due to deformation of an elastic body forming the second link element, such as a spring, when the arm mounts move from the first use position to the second use position.
Still another link mechanism that allows the entire armrests, that is, the arm mounts and arm supports, to move in a substantially regular path around a person in a chair between the first and second use positions is provided with a controlling means that rotates the arm supports, together with the arm mounts, between the chair body and arm supports around the person. To allow the armrests to move smoothly without interfering with the person, the arm supports are preferably curved or bent to prevent them from interfering with the person when he or she moves between the first and second use positions.
To ensure that the arm mounts serve as armrests when a person in a chair such as that described above operates a personal computer, it is preferable that a pair of armrests be disposed on both sides of the chair body, and that the ends of the arm mounts butt against each other when the pair of arm mounts is placed in the second use position.
As described above, a chair according to the present invention has armrests on the sides of the chair body. Using controlling means provided in the armrests or between the chair body and arm supports, the armrests, that is, the arm mounts supported by the arm supports attached to the sides of the chair body, are controlled so that at least the arm mounts move around the person in the chair in a substantially regular path between the first use position on the sides of the person and the second use position in front of the person. Thus, when he or she is not at his or her desk, the person in the chair can place his or her arms on the arm mounts in the first use position to assume a comfortable position. In addition, when he or she performs an operation, such as using a personal computer, at his or her desk, the person in the chair can stretch his or her arms forward on the arm mounts in the second use position nearly in front of him or her, to effectively use the arm mounts as armrests. The person in the chair can make the space between the arms wider or narrower than the width of his or her shoulders to place his or her arms on the arm mounts in the second use position, so that he or she can work more freely. Under the control of the controlling means, at least the arm mounts move in a substantially regular path through an angle of approximately 90xc2x0 or slightly greater from the first use position to the second use position. Thus, the arm mounts make only necessary movements, without protruding significantly outward or inward, enabling the person in the chair to move the armrests smoothly and stably without moving the chair back or avoiding the arm mounts, even if there is little space between the chair or person and the desk or the like.
Such a chair arrangement makes the arm mounts more stable with respect to the arm supports and allows only the arm mounts to be moved appropriately if the arm supports are used to support the arm mounts between the first and second use position, so that the mounts can move with respect to the arm supports and movement of the arm mounts can be controlled using the controlling means.
If the arm mounts are connected through the link mechanism, which serves as a supporting and controlling means, to the arm supports, the arm mounts can be effectively supported and moved in an appropriate path. Particularly if the link mechanism consists of the first and second link elements, which are rotatably attached to the connections of the arm supports and arm mounts, and the controlling means consists of the first and second link elements, with at least the first link element being used as the supporting means, the link mechanism can be provided with a simple structure. Moreover, if the tetragon formed by the straight lines connecting the four attachment holes in the first and second link elements is not a parallelogram, a link mechanism consisting of the two link elements can be used to smoothly move the arm mounts around the person in the chair when two of the four sides of the tetragon are secured.
Specifically, a simple link mechanism that moves the arm mounts in a substantially regular path around the person in the chair can be provided if arrangements are made to meet the following requirements: the first link element is adapted to rotate its holes for attachment to the arm mounts from an obliquely rear outside position to an inside position, with its holes for attachment to the arm supports at the center of rotation; the second link element is adapted to rotate its holes for attachment to the arm mounts from an obliquely rear outside position to an obliquely front outside position, with its holes for attachment to the arm supports at the center of rotation; and a straight line connecting the hole for attaching the first link element to the arm mount with the hole for attaching the second link element to the arm mount rotates between the first and second use positions, from the position at which the line is nearly in the longitudinal direction of the arm mount and to the position at which the line is nearly in the lateral direction of the arm mount.
If the first and second link elements are adapted so as to interfere with each other at or near the first and second use positions, the link mechanism can effectively be used to limit the range of rotation of the link elements.
If the second link element is adapted so as to support the arm mounts like the first link element, and these two link elements are used to uniquely determine the arm-mount path, the arm mount support strength can effectively be increased, and the arm mounts can be moved in a regular path.
If the second link element is formed using an elastic body such as a spring and the distance between the attachment holes in the second link element is changed by deforming the elastic body when the arm mounts move from the first use position to the second use position, the movement path of the arm mount can be varied slightly with the path kept substantially regular, and the arm mounts can be adapted so as to be at the first and second use positions. Thus, the arm mounts can easily be moved regardless of the physical build and position of the person in the chair.
In addition, if a controlling means is provided between the chair body and arm supports to turn the arm supports together with the arm mounts, the armrests can be moved in a substantially regular path between the first and second use positions, thus allowing the arm mounts to be used effectively as armrests. Particularly in such a case, curving or bending the arm supports so that they do not interfere with the person in the chair during arm mount movement allows the arm mounts to move smoothly.
In the above-described arrangements, if a pair of armrests is disposed on the sides of the chair so that the ends of the arm mounts butt against each other when both arm mounts are at the second use position, no gap forms between the arm mounts at the second use position, thus allowing the arm mounts to be used as reliable armrests when the person in the chair works on a personal computer with his or her arms stretched forward.